Ok, the minute I saw this I had to respond. Lots of people told me not to give my daughter a pillow but she liked it so much I just put one in there anyway. If he is 20 months old then a pillow is fine. You just shouldn't use one before they are 1. My daughter had a pillow at 1 in her crib. She wouldn't sleep otherwise. I put one in there and checked on her every once in awhile to make sure she was fine and she slept better. He is actually old enough for a toddler bed if you wanted to give him one. If he's not trying to climb out of his crib then a toddler bed might be nice for him. You still use a crib matteress though but he would have a little more freedom. My daughter loved her, but now I put her in a twin sized bed because that crib matteress was uncomfortable to her. If you wanted you could even put him in a twin bed but buy those guards that go on the sides of the bed that stop him from falling out of it. My daughter likes the twin bed because she is a lot more comfortable and theres more room. Anyway, a pillow is fine. Just find a flatter pillow, like maybe one you use all the time and put it in there with him and see how he does. I wouldn't go buy a big fluffy pillow though, just find a flatter one that already used in the house. You might want to let him have the pillow during the day also while he's watching tv or taking a nap and see how he responds to it. I hope this helps.